Drysuit Trim Problem

[hongrace]

I use TLS350 with Fourth Element Xerotherm undergarment which is a thin suit.

My understanding of trimming is that you extend your legs a bit to get you front end up and you keep your lower legs close to your butt to get front end down.

However, when I extend my legs in the preparation of a back kick, my legs float. This makes me almost impossible to practise back kick as every time I extend my legs in the loading phase, my trim is upset and I get head down legs up.

I can get back in trim if I hold my legs up and close to my butt.

Am I getting too much air in the leg sections?

I have tried a few dives with all air in the drysuit squeezed out and no air was added during descend. I still got floaty legs.

The only way I could get the trim right and back kick accomplished was to move some of my weights from waist to the thigh pockets and hold my hands along side on my thighs instead of holding them in front of me.

My gear is double with steel back plate with Scubapro Jetfins. Drysuit is with turbosole. No gaiter and no ankle weights.

Why do my legs float?

Thanks.

 

[rhwestfall]

[-]It may not be that your legs are floating, but that your center of gravity is far forward. What size/length/material are the doubles? How much weight are you carrying?[/-]

never mind, mis-read post....

 

[hongrace]

The tanks are AL80 with 4 lbs weight on belt.

---------- Post added December 5th, 2012 at 10:19 PM ----------

My trim is good on descend and at depth as long as I do not extend my legs.

 

[DA Aquamaster]

I really prefer a rock boot type of boot as it helps reduce the amount of gas in your feet.

If the legs are a little large you could have issues with excess gas migrating there.

In either case dump all the air out of the suit so you are slightly squeezed and see how it trims, and more importantly, whether you get a trim shift from extending your feet, rather than drawing them up 90 degrees to your thighs. Personally, If my trim changed with that amount of foo t/leg movement I'd be displeased as it would mean trim changes when executing or transitioning to/from different kicks in a cave where I want to keep the trim neutral all the time.

 

[hongrace]

Thanks DA. I had all (as much as I could do) air squeezed out and did not add air to remove squeeze underwater. Every time I extended the legs, trim changes from horizontal to legs up. I don't know if air is the culprit here but this is against my understanding of trimming. So it must be air going into my legs. But since I had all air squeezed out, where did it come from?

 

[Wayne at DiveSeekers]

Keys to Trim - Arms out in front, head up, crunch butt cheeks, ankles closer to your butt and point toes. Majority of the time when legs are dropping, your ankles are too far away from your butt. Legs dropping when stopping is common when first learning, small loss of focus, keep at it and it will come.

Reading your post, it sounds like this is only happening when trying to Reverse Kick. If yes, this is common when first learning to Reverse Kick. I find that when divers are starting to learn this kick, divers forget to keep their toes pointed, thus finds are staight up in the water and they start going up. The other thing, don't worry about trim at first (that will come), just focus on getting the backward momentum. The other helpful hint, try to exhale when you start the kick. Stay away from ankle weights (weight down legs), if still having difficulty, try some gaitors (use as last option).

Hope this is helpful, Try to get someone to video (without it, learning process is longer) you and look for the things that I mentioned.

 

[hongrace]

Hi Wayne, Thank you for your advice. I will try to have someone videoing me this weekend in the pool. When you said toes pointed, did you mean pointed like ballerina dancing on toes?

 

[TSandM]

It's really common, when people are learning to back kick, for them to get the ends of their fins pointing UP, rather than pointing straight back. In that case, each time to try to kick, you pull yourself a little backwards but also up (and up feet-first, which would just like having floaty feet). We call that the "backwards shrimp-dance", and most of us have done it

Your understanding of the effect on trim of body position is minorly faulty, as well. You can't escape the inexorable nature of physics and levers. If your feet are negative, then putting them out behind you will give them a longer level to pull your body feet-down/head-up; but if they are floaty (eg. have too much air in them) then putting them further from your body will increase their tendency to pull you UP. Deciding what the posture change is doing has to be done in isolation from kicking -- you have to get yourself completely stable and quiet in horizontal trim, and then carefully change the position of the feet, and see what happens.

Most of the changes one needs to make in static weighting for perfect horizontal trim are counterintuitive, so it really pays off to have someone watch and video, and to pay close attention to things like head position, arm position, and whether you are dropping your knees, because all of these things will be affecting your trim as well.

 

[elan]

Extending your legs does not mean they will automatically drop. Your head should also be up and the back arched. Also leg extension only works when your fins are denser then water, if you have floaty fins it will be quite the opposite. A problem I have seen often when people were learning to back kick - they were dropping the head as well causing the body to turn head down.

 

[tye1138]

Trilam suits have air shifting issues because they normally have a pretty loose fit.

Dawning them can be tricky because getting as much air out as possible can be more difficult then you think.

You can't rely on the exhaust valve to get all the air out. You've gotta take your finger and break the seal with your neck, then get into a squat position and squeeze the air out of your suit. Before you stand back up, refit the neck seal and you should have mostly all the air out of your suit.

The suggestion above about wearing rock boots is A+, thats important on a suit with no built in boot like the DUI.

The other part is fin type. A lot of fins are positive or neutral. Its nice to have a set of fins which are negative for dry suits. I know it sounds counter intuitive, but it does help a great deal. I believe the ScubaPro Jet fins are negative, so thats a good start already.